This invention relates to a child safety seat particularly for infants and children for use in vehicles. Even more particularly, this invention relates to such a child safety seat that has a base attachable to a vehicle seat and has a child safety seat connected to the base in such a way that the child safety seat, in response to a sudden deceleration of the vehicle, moves through a controlled path that reduces or avoids injury to an infant or child occupying the child safety seat. This invention also relates to an improved device for tightening a seat belt in response to the movement of the seat through a controlled path.
Known devices for tightening a seat belt in response to movement of the seat have required elaborate apparatus. For example, the device disclosed in U.S. Pat. No. 4,738,485, to Rumpf ("the Rumpf patent"), requires a cable and pulley system which is completely separate from the seat belt itself.
FIG. 1 of the Rumpf patent shows a vehicle seat apparatus 20 including a seat 30, and an occupant seat belt restraint 40, attached to seat 30. The seat 30 is mounted in tracks 62 and 64, such that the entire seat 30 moves forward and the front of seat 30 moves upward upon sudden deceleration of the vehicle.
Upon forward motion of the seat, an actuator mechanism 142 rotates a drive gear 132 to wind the belt webbing 82 onto spool 134 to tighten the belt. The actuator mechanism 142 includes a cable 146 which is coupled on one end to a retractor 150 which is coupled to a point on the vehicle seat apparatus 20 which does not move in response to the deceleration of the vehicle. The cable extends from retractor 150 around pulley 144 through the back of seat 30 and is coupled on its other end to a drive bar 148. As seat 30 moves forward, pulley 144 moves forward relative to retractor 150, thereby causing cable 146 to pull down on drive bar 148. This rotates drive gear 132, which causes shoulder belt 82 to be tightened around the occupant.
The complexity of the apparatus of the Rumpf patent makes the device expensive and space consuming. In addition, the complexity of the device increases likelihood of failure of one of the components and, therefore of the entire apparatus. There is thus a need for a simple, reliable apparatus, requiring a minimum of space, for tightening a seat belt in response to movement of the seat.